Balanced pressure pump



2- Sheets-Sheet l INVENTOR.

Sept 21, 1965 P. w. scHLossr-:R

BALANCED PRESSURE PUMP Filed Nov. 5, 1962 Sept 21, 1965 P. W. scHLossER 3,207,080

BALANGED PRESSURE PUMP Filed Nov. 5, 1962 2 Sheets-Sheet 2 SUMP INVENTOR. PA UL WSCHLOSSER United States Patent O 3,267,080 BALANCED PRESSURE PUMP Paul W. Schlosser, Chicago, Ill., assigner to Panther Pumps & Equipment Co., Inc., Chicago, lll., a corporation of Illinois Filed Nov. 5, 1962, Ser. No. 235,297 7 Claims. (Cl. 11B-452) The present invention relates to iluid operated diaphragm pumps, and it relates more particularly to a new and improved balanced diaphragm pump which is particularly suited for pumping viscous liquids such as paint, but which may be used for pumping other more abrasive materials as well as for pumping highly corrosive liquids.

In order to render paint and like liquids sufficiently iluid to permit easy passage thereof through the nozzle of a spray gun it has been common practice to control the temperature of the paint. Accordingly, during winter a heating unit is frequently used to raise the temperature of the paint to a desired value. Hence, a spray gun system commonly includes a pumping unit for feeding the paint under pressure to the spray gun and a separate heating unit for heating the paint. It would be desirable to eliminate the heater from this system by providing a combined pump and heating unit.

In a diaphragm type of pump which is driven by a pressurized hydraulic lluid the hydraulic fluid may be so utilized that it has a relatively high temperature at the time it is being pumped into the drive chamber of the diaphragm pump. This being the case, if the diaphragm element is a good heat conductor, heat may be transferred from the hydraulic lluid to the paint as it passes through the pumping chamber.

Various types of pumps, including diaphragm pumps, have been designed and used for pumping paint and other viscous and abrasive liquids, but the cost of such devices has been relatively high, particularly in the case of the diaphragm operated pumps, thereby limiting their use to very special situations wherein other types of pumps are not applicable. Because, however, of the particular advantage of a diaphragm pump when used in the pumping of viscous and abrasive liquids, it would be desirable to provide a diaphragmpump which would be simple in construction and compact in design so asto appreciably reduce the cost of manufacturing such apparatus.

f Therefore, a principal object of the present invention is to provide a new and improved iluid operated pump.

Another object of the present invention is to provide a new and improved balanced pressure pump for pumping liquids.

A further object of the present invention is to provide a double-acting diaphragm pump which is simple in construction, compact in design, and which can be manufactured at a sufficiently low cost to make it competitively marketable.

Another object of the present invention is to provide a new and improved seal for hermetically sealing a reciprocating rod to a relatively fixed member, through which it extends.

Further objects and advantages and a better understanding of the present invention may be had by reference to the following detailed description taken in connection with the accompanying drawings in which:

FIG. l is a top plan view of a double-acting diaphragm pump embodyingA certain features of the present invention and wherein the control valve is partly broken away to show the internal construction thereof;

FIG. 2 is a side elevational view, somewhat reduced, of the pump of FIG. 1;

FIG. 3 is a vertical cross-sectional View of a portion of the pump of FIG. l taken along the line 3-3 thereof;

3,207,080 Patented Sept. 21, 1965 FIG. 4 is a schematic diagram of the pump of FIG. 1; and

FIG. 5 is a sectional view taken along the line 5 5 of FIG. 3 and particularly showing a reciprocating seal embodying certain features of the present invention.

Referring now to the drawings and particularly to FIGS. l and 2 thereof, there is shown a pump assembly 10 comprising as its principal elements a pair of pumping units 12 and 14 which are xedly mounted on a base plate 16 and which are hydraulically connected to a control valve 18 by suitable means, not shown in FIG. 1, for pumping a liquid, such, for example, as paint, from inlet ports 20 and 22, respectively, to outlet ports 24 and 26, respectively. As more fully described hereinafter in connection`with FIG. 4, the control valve 18 is connected between the outlet of a hydraulic fluid pump connected to the inlet port 28 and a hydraulic iluid sump connected to the outlet port 30. A support bar 31 is fastened at its ends to the units 12 and 14. The spool 32 of the control valve 18 is mechanically connected to the diaphragms in both of the pumping units 12 and 14 which are connected to operate in out-of-phase relationship. Hence, when the unit 12 is pumping fluid out of its pumping chamber, the other unit 14 is drawing fluid into its pumping chamber. At the end of each such stroke, the spool 32 is moved to its opposite position within the chamber of the control valve 18 thereby to reverse the operation of both of the pumping units 12 and 14. A more complete description of the operation of the pump 10 will be given hereinafter.

The pumping units 12 and 14 are identical in construction and, therefore, only the unit 12 need be described in detail. Therefore, referring to FIG. 3, it may be seen that the pumping unit 12 comprises a pair of dome-like castings 34 and 36 which have respective peripheral ilanges 38 and 40 secured together by a plurality of spaced-apart bolts 42. A thin walled flexible diaphragm 44 of generally circular shape is located between the castings 34 and 36 and an annular peripheral area of the diaphragm 44 is tightly compressed between the llanges 38 and 40 thereby to provide a tight seal between a pumping chamber 46 located on one side of the diaphragm 44 and a drive chamber 48 located on the opposite side of the diaphragm 44. The flange 40 has a larger `ou-ter radius than the ilange 38, whereby it may be provided with a ilat surface 50 along the bottom edge to facilitate welding thereof to the base plate 16 to support the unit 12 thereon.

The cast section 34 is provided with an axial aperture 52 in which a nipple 54 is secured to provide an inlet port to the pumping chamber 46. At the top of the casting 34 is provided a raised boss 56 which is provided with a bore 58 in which a nipple 60 is secured to provide an outlet port. Each of the nipples 54 and 60 preferably includes a suitable valve seat and ball valve member spring biased to provide a pressure actuated check valve, the nipple 54 permitting unidirectional llow of fluid into the chamber 46 and the nipple 60 permitting unidirectional ilow of fluid out of the chamber 46. Separate check valves may be provided for this purpose if desired.

In order to admit and emit hydraulic fluid to and from the drive chamber 48, the casting 36 is provided with a bore 62 extending upwardly through a boss 64. A simple nipple connector 66 is threadedly received therein.

In accordance with an important feature of the present invention, the diaphragms in each of the pumping units 12 and 14 are mechanically connected together to insure that they reciprocate in exact correspondence and, moreover, to provide a common interconnecting member for controllably positioning the spool 32 in the control valve 18. Accordingly, a tie rod 68, which is in the form of a solid cylinder, extends through a sealing member 70 which is in turn sealably secured in an axial hole 72 in the casting 36 and is connected to the center portion of the diaphragm`44. The diaphragm 44, which is preferably very thin in cross section and formed of a good heat conducting ilexible material such, for example, as rubber, is provided with a centrally disposed aperture '76 through which the end portion of the rod 68 extends. The end of the rod 68 is threaded and a nut '78 is secured thereto with a washer-like member 80 positioned over the rod in abutment with the face of the nut 78. A similar Washer-like plate 82 is positioned on the rod 68 on the opposite side of the diaphragm 44 and a nut 84 is threaded onto the end of the rod 68 to tightly compress the diaphragm 44 between the members 80 and 82.

In order to prevent wear on the diaphragm as it flexes back and forth between the chambers 46 and 48, the members 80 and 82 are provided with substantially semispherical diaphragm facing surfaces 86. Consequently, there is no small connecting area about which the diaphragm 44 must flex an appreciable amount as it moves back and forth within the unit 12. Therefore, no substantial wear occurs and the life of the diaphragm 44 is extremely great.

The rod 68 and a corresponding rod 88 in the pumping unit 14 are each threadedly connected to an arm 90 to which a pair of nuts 92 and 94 are fixedly secured as by welding. Accordingly, as the diaphragms 44 move back and forth in the pumping units 12 and 14, the arm 90 also moves back and forth from left to right, as viewed in FIG. 1.

In order to control the operation of the control valve 18 in accordance with the position of the arm 90, a control rod 96 is axially connected to the valve spool 32 and loosely extends through a hole 98 in the arm 90. A pair of stop washers 100 and 102 are Xedly secured as by welding to spaced-apart positions on the rod 96 and a pair of coil springs 104 and 106 are positioned over the rod 96 between the arm 98 and the respective stops 100 and 102. As the rod 90 moves toward the left, as it is illustrated in FIG. 1, the spring 104 is gradually compressed to exert an increasing force toward the left, tending to move the spool from its right-hand position which it occupies in FIG. 1, and in which it is supplying pressurized hydraulic fluid to the unit 12, to its left-hand position, wherein it connects the drive chamber of the unit 12 to the sump and connects the pressurized fluid to the drive chamber of the unit 14.

The spool 32 is held in one or the other of its two extreme positions by means of a ball detent arrangement comprising a spherical member 108 which is pressed by means of a light coil spring 110 into one or the other of a pair of spaced-apart axial grooves 112 and 114 in a rod 116 extending axially to the right from the spool 32. The ball detent is adjusted by means of a machine screw 118 so that it exerts a suicient holding influence on the spool 32 to maintain it in one or the other of its two stable positions until the diaphragms 44 have reached the point at which it is desired to reverse their strokes. At this time, one or the other of the springs 104 and 106 is sufficiently compressed so that the axial force exerted on the rod 96 overcomes the holding force of the detent assembly, thereby to push the ball 108 against the spring 110 into the associated bore to free the rod 116 for movement into the other position where the ball 108 is forced by the spring 110 into the other one of the grooves 112, 114.

In order to insure that the spool is not stopped at an intermediate position, it is desirable to use a ball 108 having a diameter substantially less than the diameter of the grooves 112 and 114. In this way, a substantial holding force can be produced on the rod 116 without employing a very high spring pressure on the ball. Therefore, when the spring pressure is overcome and the ball 108 is moved against the spring 110, the frictional force exerted through the ball 108 on the portion of the rod 116 4, between the grooves 112 and 114 is extremely small and less than the force exerted on the rod 96 by the expanding spring 104, 106 which has previously been compressed.

Consider now the operation of the pump 10 during a typical pumping cycle. Referring to FIG. 4, there is illustrated a schematic diagram of the pumping system shown in greater detail in FIGS. 1-3. As shown, the control valve 18 has its port 30 connected via a conduit 130 to the drive chamber of the pumping unit 12. In like manner, the port 28 is connected by means of a conduit 132 to the drive chamber of the pumping unit 14. A suitable pump 134 is connected between a hydraulic sump 136 and the inlet to the control valve 18. The return port of the control valve 18 is connected by means of a return conduit 138 to the sump 136. If desired, a controllable by-pass line 140 between the conduit 138 and the sump pump 134 may be provided to control the temperature of the hydraulic fluid which is being pumped to the drive chambers in the units 12 and 14 thereby to control the temperature of the hydraulic Huid and hence that of the liquid being pumped by the system.

The control valve 18 and the remainder of the system are illustrated in FIG. 4 in the same condition as they are illustrated in FIGS. 1 through 3, and consequently the hydraulic fluid pumped by the pump 134 is being fed through the valve 18 and the conduit 130 to the drive chamber in the unit 12. Accordingly, the diaphragm 44 shrown in FIG. 3 is being forced to the left, thereby to force the paint or other liquid contained in the pumping chamber therein out through a check valve 142 to a common outlet manifold 144. The check valve 146 connected between the pumping unit 12 and the paint or other liquid supply prevents the liquid from the pumping unit 12 from being returned to the supply. At this same time, the diaphragm in the pumping unit 14 is being pulled to the vleft by means of the rods 68 :and 88 thereby to force the hydraulic fluid in the pumping chamber thereof through the conduit 132, the valve 18 and the conduit 138 to the sump 136 or to the by-pass line 140 as the case may be. The paint or other liquid to be pumped is at this time being sucked through t-he check valve 148 from the supply source into the pumping chamber. A check valve 150 connected between the pumping unit 14 and the common manifold 144 is closed at this time to prevent pulling paint from the manifold 144 back into the pumping unit 14.

With the valve 18 in this position, the rods 68 and 88 are moving towards the left thereby compressing the spring 144 until such time as the force exerted on the control rod 96 becomes sufficiently great to overcome the holding force exterted by the ball detent arrangement thereon. When the holding force is overcome and the ball 108 is forced out of the groove 112 against the spring 110, the spool 32 moves to the left to its other stable position wherein the ball 108 is received in the groove 114. At this time the outlet of the pump 134 is connected through the valve 18 to the conduit 132 and the conduit 130 is connected through the valve 18 to the conduit 138 connecting to the sump 136 and/or the by-pass line 140. Accordingly, hydraulic pressure is exerted on the diaphragm in the pumping unit 14 to force it to the right, thereby expelling the paint or other liquid through the check valve 150 into the common outlet manifold 144. When the coil spring 106 has been sufliciently compressed to exert a force on the rod 96 which overcomes the holding force exerted by the ball detent arrangement thereon, the spool 32 is moved to the right until the ball 108 again seats in the groove 112.

Should the spool 32 become jammed in the intermediate position, both of the pumping chambers in the units 12 and 14 are partially connected to the return conduit 138 and no damage can be caused to the various parts of the unit.

Referring to FIG. 5, there is shown in greater detail the sealing device 70 which is threadedly secured to the casting 36 and in which the rod 68 axially reciprocates. As there shown, the seal 70 comprises a generally tubular body portion 156 having an external thread thereon and having .a hexagonal head 158 for facilitating the mounting of the same within the threaded bore 72 in casting 36. The bore through the unit 70 is provided with an enlarged center section 160 thereby to provide reentrant annular llanges 162 and 4164 at the respective ends thereof. The internal diameters of the flanges 162 and 164 are substantially larger than the external diameter of the rod 68 so that there is no engagement between the anges 162 and 164 and the rod 68. Located within the enlarged center section 160 is a tubular sealing gasket 166 which resiliently engages the rod 68. The gasket material 166 is a combination of silicone rubber, in which a mica powder is embedded.

In order to construct the seal 70 the rod 68 is placed within the tubular member 156 and a mixture of two parts silicone rubber and one part mica powder, including a curing agent, is placed in the liquid state in the cavity 160 surrounding the rod 68. The silicone is then permitted to cure. The mica powder provides the necessary lubrication to permit sliding of the rod 68 through the seal 70 and the expansion of the silicone rubber during curing provides a tight pressure t between the gasket 166 and the rod 168. This seal will withstand pressures at least as great as 1000 p.s.i. at temperatures as high as 500 F. Moreover, the seal is eifective at pressures approaching 0 p.s.i.

While the present invention has been described in connection with a particular embodiment thereof, it will be understood that those skilled in the art may make many changes and modifications without departing from the true spirit and scope of the present invention. Therefore, it is intended by the appended claims to cover all such changes and modifications which fall within the true spirit and scope of the invention.

I claim:

1. In apparatus of the type described, the combination comprising means defining a irst chamber, means defining a second chamber, a rst flexible diaphragm connected across said rst chamber and separating said iirst chamber into a pumping chamber and a drive chamber, a second exible diaphragm connected across said second chamber and separating said second chamber into a pumping chamber and a drive chamber, a rigid connection between said diaphragms for insuring synchronous operation of both diaphragms, a source of pressurized iluid, a spool control valve having a control member, said valve connecting said source to said drive chamber in said first chamber when said control member of said valve is in a first operative position and for connecting said source to said drive chamber in said second chamber when said control member of said valve is in a second operative position, `and a mechanical connection between said rigid connection and said control member to operate said valve in accordance with the positions of said diaphragms in said chambers.

2. The combination of claim 1 wherein said mechanical connection includes spring means and associated releasable detent means for causing abrupt movement of said control member when said diaphragms move into predetermined positions..

3. The combination of claim 2 wherein said control member is an axially movable rod, and said mechanical connection includes a member movable along said rod, and said spring means is connected between said movable member and said rod.

4. The combination of claim 3 wherein said detent means includes a ball mounted for movement normal to said rod, said rod having at least one annular groove,

said ball being movable into and out of said annular groove in said rod, said ball having a diameter less than the diameter of said groove, and spring means urging said ball into said groove.

5. In apparatus 4of the type described for pumping liquids at several hundred p.s.i. pressure, the combination comprising means defining at least two housing chambers capable of withstanding said pressure, thin walled, flexible diaphragm means having portions dividing each of said housing chambers into a pumping chamber and a drive chamber, a rigid driving connection between said portions for insuring substantially synchronous operation of said diaphragm portions, a source of pressurized fluid at said pressure, a spool control valve having a control member for connecting said source to the drive chamber in one `of said housing chambers when said control member of said Valve is in one operative position for connecting said source to the drive chamber in another of said housing chambers when said control member of said valve is in another operative position, and a driving connection between said rigid connection and said control member to operate said valve in accordance with the position of at least one of said portions of said diaphragm means in said housing chambers.

6. A system including a pump for pumping liquids comprising housing means forming a pair of chambers, said pumping causing heating of the liquids, a thin walled heat conductive flexible diaphragm in each of said chambers, each said diaphragm sealably separating said chambers into a liquid pumping chamber and a hydraulic drive chamber, a hydraulic connection to said drive chamber, a sump, means for controllably pumping hydraulic iluid from said sump to said hydraulic connection, means for controllably returning hydraulic fluid from said hydraulic connection to said sump, means for recirculating a controlled amount of said hydraulic uid directly from said hydraulic connection to said pumping means to bypass said sump whereby the temperature of the liquid pumped through said pump may be controlled.

7. A heat exchange system including a high pressure pump for pumping liquids including a housing forming a chamber, said pumping causing heating of the liquids, a thin walled heat conductive exible diaphragm separating said chamber into a liquid pumping chamber and a hydraulic drive chamber, hydraulic drive means connected to said pump and including connecting means to and from said drive chamber for circulating hydraulic uid to and from said drive chamber and driving said diaphragm and the liquid in said pumping chamber, means for cooling the liquid, and means for by-passing the liquid to said cooling means whereby the temperature of the liquid pumped may be controlled.

References Cited by the Examiner UNITED STATES PATENTS 326,545 9/ 85 Class et al 230-170 X 491,116 2/93 Keeney 103-152 1,667,138 4/28 Barks 91--346 1,905,284 4/ 33 Heitger. 2,237,758 4/ 41 Kurzweil 277-182 2,260,306 10/41 Ferguson 103-152 2,402,114 6/ 46 Le Clair 277-182 2,673,525 3/54 Lucas 103--152 2,703,055 3/55 Veth et al. 103-152 FOREIGN PATENTS 744,815 1/ 3 3 France.

LAURENCE V. EFNER, Primary Examiner.

WARREN E. COLEMAN, ROBERT M. WALKER,

Examiners. 

1. IN APPARATUS OF THE TYPE DESCRIBED, THE COMBINATION COMPRISING MEANS DEFINING A FIRST CHAMBER, MEANS DEFINING A SECOND CHAMBER, A FIRST FLEXIBLE DIAPHRAGM CONNECTED ACROSS SAID FIRST CHAMBER AND SEPARATING SAID FIRST CHAMBER INTO A PUMPING CHAMBER AND A DRIVE CHAMBER, A SECOND FLEXIBLE DIAPHRAGM CONNECTED ACROSS SAID SECOND CHAMBER AND SEPARATING SAID SECOND CHAMBER INTO A PUMPING CHAMBER AND A DRIVE CHAMBER, A RIGID CONNECTION BETWEEN SAID DIAPHRAGMS FOR INSURING SYNCHRONOUS OPERATION OF BOTH DIAPHRAGMS, A SOURCE OF PRESSURIZED FLUID, A SPOOL CONTROL VALVE HAVING A CONTROL MEMBER, SAID VALVE CONNECTING SAID SOURCE TO SAID DRIVE CHAMBER IN SAID FIRST CHAMBER WHEN SAID CONTROL MEMBER OF SAID VALVE IS IN A FIRST OPERATIVE POSITION AND FOR CONNECTING SAID SOURCE TO SAID DRIVE CHAMBER IN SAID SECOND CHAMBER WHEN SAID CONTROL MEMBER OF SAID VALVE IS IN A SECOND OPERATIVE POSITION, AND A MECHANICAL CONNECTION BETWEEN SAID RIGID CONNECTION AND SAID CONTROL MEMBER TO OPERATE SAID VALVE IN ACCORDANCE WITH THE POSITIONS OF SAID DIAPHRAGMS IN SAID CHAMBERS. 